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Article type: Cover
2001 Volume 102 Issue 6 Pages
Cover1-
Published: March 20, 2001
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Article type: Appendix
2001 Volume 102 Issue 6 Pages
App1-
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Article type: Appendix
2001 Volume 102 Issue 6 Pages
F1-F2
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[in Japanese]
Article type: Article
2001 Volume 102 Issue 6 Pages
F3-F5
Published: March 20, 2001
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A. Purwanto, T. Endoh, T. Morozumi, T. Onogi
Article type: Article
2001 Volume 102 Issue 6 Pages
F6-F11
Published: March 20, 2001
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We examine CP violating phases in 3×6 MNS matrix of the seesaw model. Independent number of the phases is six and their effects on lepton asymmetry and neutrino oscillations are studied.
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Toshihiko Ota
Article type: Article
2001 Volume 102 Issue 6 Pages
F12-F14
Published: March 20, 2001
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Morimitsu TANIMOTO
Article type: Article
2001 Volume 102 Issue 6 Pages
F15-F21
Published: March 20, 2001
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We have discussed the lepton mass matrices with the U(1) flavor symmetry, which leads to the large mixing angle MSW solution of solar neutrinos. We also comment on the non-abelian flavor symmetry.
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Taichiro Kugo, Masako Bando, Koichi Yoshioka
Article type: Article
2001 Volume 102 Issue 6 Pages
F22-F26
Published: March 20, 2001
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A novel relation is found which holds experimentally very well and gives the 2-3 lepton mixing angle θ_<μτ> in terms of quark masses and CKM mixing: tanθ_<μτ> = (m_b /m_s)V_<cb>. This relation is a kind of SO(10) GUT relation similar to the celebrated bottom-tau mass ratio in SU(5), and seems to give an important clue for the final grand unified theory.
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T. TESHIMA, T. ASAI
Article type: Article
2001 Volume 102 Issue 6 Pages
F27-F32
Published: March 20, 2001
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We assume the universal Yukawa coupling (democratic mass matrix) with small violations for quark , charged lepton and neutrino masses. We could reproduce the mass hierarchy and V_<CKM> matrix for quarks precisely. We adopt the see-saw mechanism for explanation of the smallness of neutrino masses and introduce the right-handed Majorana and left-handed Dirac neutrinos. Assuming the democratic mass matrix with small violations for both Majorana and Dirac neutrinos, we can get the hierarchy of charged lepton and effective neutrino masses and the large mixing of neutrinos expressed in V_<NMS>.
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Teruyuki Kitabayashi
Article type: Article
2001 Volume 102 Issue 6 Pages
F33-F41
Published: March 20, 2001
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We have constructed two SU(3)_L×U(1)_N gauge models with the L' = L_e - L_μ - L_τ symmetry, which accommodate tiny neutrino masses generated by one-loop and two-loop radiative effects. The heavy neutral leptons and heavy charged leptons are employed to specify the lepton triplets in SU(3)_L, respectively, accompanied by (φ^0, φ^-, h^+) and (φ^+,φ^0, h^+), where φ stands for the standard Higgs scalar and h^+ is a key ingredient for radiative mechanisms. From our numerical calculations, we find that both our models are relevant to yield the VO solution to the solar neutrino problem.
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Teruyuki Kitabayashi, Masaki Yasue
Article type: Article
2001 Volume 102 Issue 6 Pages
F42-F51
Published: March 20, 2001
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Phenomena of neutrino oscillations are discussed on the basis of two-loop radiative neutrino mechanism. Neutrino mixings are experimentally suggested to be maximal in both atmospheric and solar neutrino oscillations. By using L_e - L_μ - L_τ (≡ L')-conservation, which, however, only ensures the maximal solar neutrino mixing, we find that two-loop radiative mechanism dynamically generates the maximal atmospheric neutrino mixing and that the estimate of Δm^2_⊙/Δm^2_<atm>〜εm_e/m_τ explains Δm^2_⊙/Δm^2_<atm> ≪ 1 because of m_e/m_τ ≪ 1, where ε measures the breaking of the L'-conservation. Together with Δm^2_<atm> ≈ 3× 10^<-3> eV^2, this estimate yields Δm^2_⊙〜10^<-7> eV^2 for ε〜0.1, which corresponds to the LOW solution to the solar neutrino problem. Neutrino mass scale is given by (16π^2)^<-2>m_e,m_τ/M (M〜1 TeV), which is of order 0.01 eV.
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F. Borzumati, K. Hamaguchi, Y. Nomura, T. Yanagida
Article type: Article
2001 Volume 102 Issue 6 Pages
F52-F66
Published: March 20, 2001
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The problem of generating light neutrinos within supersymmetric models is discussed. It is shown that the hierarchy of scales induced by supersymmetry breaking can give rise to suppression factors of the correct order of magnitude to produce experimentally allowed neutrino spectra.
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Yasutaka Takanishi
Article type: Article
2001 Volume 102 Issue 6 Pages
F67-F81
Published: March 20, 2001
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What we call the Anti-GUT model is extended a bit to include also right handed neutrinos and thus make use of the see-saw mechanism for neutrino masses. This model consists in assigning gauge quantum numbers to the known Weyl fermions and the three see-saw right handed neutrinos. Each family (generation) is given its own Standard Model gauge fields and a gauged field coupled to the B - L quantum number for that family alone. Further we assign a rather limited number of Higgs fields, so as to break these gauge groups down to the Standard Model gauge group and to fit w.r.t. order of magnitude the spectra and mixing angles of the quarks and leptons. We find a rather good fit, which for neutrino oscillations favour the small mixing angle MSW solution, although the mixing angle predicted is closest to the upper side of the uncertainty range for the measured solar neutrino mixing angle.
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[in Japanese]
Article type: Article
2001 Volume 102 Issue 6 Pages
F82-F98
Published: March 20, 2001
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Masako BANDO
Article type: Article
2001 Volume 102 Issue 6 Pages
F99-F107
Published: March 20, 2001
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1) Introduction 2) From Where does the Power Law Hierarchy Come? 3) Family Quantum Number Assignment 4) Mystery of Neutrino Masses and Mixings 5) Neutrino Mass Matrix and Family Structure
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Takeo Matsuoka, M. Matsuda
Article type: Article
2001 Volume 102 Issue 6 Pages
F108-F124
Published: March 20, 2001
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We showed that the characteristic patterns of fermion masses and mixings can be under-stood in the framework of string inspired SU(6)×SU(2)_R model. This model contains two key ingredients. The first is the flavor symmetry which generates mass hierarchies via Froggatt-Nielsen mechanism. The second is the appearance of large D^c-g^c and L-H_d mixings. The mass hierarchy of up-type quarks is a direct result of the flavor symmetry. On the other hand, for down-type quarks there appears a mixing between D^c and g^c, which are both SU(2)_L-singlets. Due to large D^c-g^c mixing mass hierarchy of down-type quarks differs from that of up-type quarks. For leptons a mixing between SU(2)_L-doublets L and H_d occurs. In the neutrino sector Dirac mass hierarchies cancel out in large part due to seesaw mechanism. Thus we obtain the mass hierarchies m_u:m_c:m_t 〜 λ^7:λ^4:1, (93) m_d:m_s:m_b 〜λ^7:λ^6:λ^3, (94) m_e:m_μ:m_τ 〜 λ^7:λ^<4.5>:λ^2, (95) m_<ν1>:m_<ν2>:m_<ν3> 〜 λ^6:λ^5:λ^4. (96) Nontrivial V_<CKM> is induced by large D^c-g^c mixings. In the present model V_<ub> is naturally suppressed compared to V_<td>. We understood the reason why the V_<CKM> is nearly equal to unity but not exactly unity. Further we obtain a phenomenologically viable relation V_<td> = V_<cd>・V_<ts>. For V_<MNS> the present model can yield a large mixing angle solution with tanθ_<12>, tanθ_<23> = Ο(√λ).
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[in Japanese]
Article type: Article
2001 Volume 102 Issue 6 Pages
F125-F134
Published: March 20, 2001
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[in Japanese]
Article type: Article
2001 Volume 102 Issue 6 Pages
F135-F141
Published: March 20, 2001
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Naoyuki Haba
Article type: Article
2001 Volume 102 Issue 6 Pages
F142-F144
Published: March 20, 2001
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The quantum effects of lepton flavor mixing angles can be easily estimated by using the technique in Ref.[1]. The cases of hierarchical or the opposite signs between the generations guarantee stable mixing angles against quantum corrections. We also show that physical Majorana phases connect the "stable" region with the "unstable" region.
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Article type: Index
2001 Volume 102 Issue 6 Pages
47-48
Published: March 20, 2001
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Article type: Index
2001 Volume 102 Issue 6 Pages
49-
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Article type: Index
2001 Volume 102 Issue 6 Pages
49-
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Article type: Appendix
2001 Volume 102 Issue 6 Pages
App2-
Published: March 20, 2001
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Article type: Appendix
2001 Volume 102 Issue 6 Pages
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Published: March 20, 2001
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Article type: Cover
2001 Volume 102 Issue 6 Pages
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Published: March 20, 2001
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Article type: Cover
2001 Volume 102 Issue 6 Pages
Cover3-
Published: March 20, 2001
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